Use SPDX license format and remove obsolete badge info

Author: atouchet

Cargo.toml

@@ -3,7 +3,7 @@
 name = "pkg-config"
 version = "0.3.24"
 authors = ["Alex Crichton <alex@alexcrichton.com>"]
-license = "MIT/Apache-2.0"
+license = "MIT OR Apache-2.0"
 repository = "https://github.com/rust-lang/pkg-config-rs"
 documentation = "https://docs.rs/pkg-config"
 readme = "README.md"
@@ -13,8 +13,5 @@ Cargo build scripts.
 """
 keywords = ["build-dependencies"]
 
-[badges]
-travis-ci = { repository = "rust-lang/pkg-config-rs" }
-
 [dev-dependencies]
 lazy_static = "1"